Floor

We explain what soil is and how it is composed. Also, classification of soils and their different characteristics.

What is soil?

The ground is the shallowest portion of the earth's crust made up mostly of rock waste from erosive processes and other physical and chemical alterations, as well as organic matter resulting from the biological activity that takes place on the surface.

The soil is the most visible portion of planet Earth, where we plant crops, build our houses and bury our dead. It is about an extremely varied and multiform surface on which climatic phenomena such as rain, wind, etc. occur.

Likewise, the soil is the scene of complex chemical and physical processes, as well as an underground ecosystem of small animals and abundant microorganisms, whose presence directly impacts its fertility.

The floors They are formed by the destruction of rock and the accumulation of materials different over the centuries, in a process that involves numerous physical, chemical and biological variants, which results in an arrangement of well-differentiated layers, like those of a cake, observable at the points of failure or fracture of the Earth's crust. .

See also: Soil pollution

How is the soil composed?

Soil is composed of solid, liquid and gaseous ingredients, such as:

• Solid. The mineral skeleton of the soil is mainly composed of rocks, such as silicates (micas, quartz, feldspars), iron oxides (limonite, goethite) and aluminum (gibbsite, boehmite), carbonates (calcite, dolomite), sulfates (aljez), chlorides, nitrates and solids of organic or organic-mineral origin, such as different types of humus.
• Liquids. Water abounds in the soil, but not always in its pure state (as in deposits) but loaded with ions and salts and various organic substances. Water in the soil moves by capillarity, depending on the permeability of the soil, and transports numerous substances from one level to another.
• Gaseous. The soil has several atmospheric gases such as oxygen (O₂) and carbon dioxide (CO₂), but depending on the nature of the soil it may also have the presence of gaseous hydrocarbons such as methane (CH₄) and nitrous oxide (N₂EITHER). Soil gases are tremendously varied.

Soil characteristics

The properties and characteristics of the soil are enormously varied, according to the type of soil and the particular history of the region where it is located. But broadly speaking we can identify the following characteristics:

• Variability. Soils generally have components that are not very homogeneous in their size and constitution, so despite appearing as a homogeneous mixture, in reality they have rocks and elements of different sizes and diverse nature.
• Fertility. The possibility of soils to host nutrients derived from nitrogen, sulfur and other elements of importance for plant life is called fertility and is related to the presence of water and organic matter, and to the porosity of the soil.
• Mutability. Although soil change processes are long-term and we cannot verify them directly, it is true that they are in constant physical and chemical mutation.
• Solidity. Soils have different physical properties, including solidity and texture: some are more compact and rigid, others more malleable and soft, depending on their particular geological history.

Soil types

There are various types of soil, each one the result of different formation processes, the result of sedimentation, wind deposition, weathering and organic waste. They can be classified according to two different criteria, which are:

According to its structure. We can talk about:

• Sandy soils. Incapable of retaining water, they are scarce in organic matter and therefore not very fertile.
• Limestone soils. They are abundant in calcareous minerals and therefore in salts, which gives them hardness, aridity and whitish color.
• Humiferous soils. Made of black soil, decomposing organic matter abounds and they retain water very well, being very fertile.
• Clay soils. Composed of fine yellowish grains that retain water very well, which is why they tend to flood easily.
• Stony soils. Composed of rocks of different sizes, they are very porous and do not retain water at all.
• Mixed soils. Mixed soils, generally between sandy and clay.

According to their physical characteristics. We can talk about:

• Lithosols. Thin layers of soil up to 10cm deep, with very low vegetation and also called “leptosols”.
• Cambisols. Young soils with initial accumulation of clays.
• Luvisols. Clay soils with a base saturation of 50% or higher.
• Acrisols. Another type of clay soil, with base saturation of less than 50%.
• Gleysols. Soils with constant or almost constant water presence.
• Fluvisols. Young soils from river deposits, generally rich in calcium.
• Rendzina. Soils rich in organic matter on limestone.
• Vertisols. Clay and black soils, located near runoff and rocky slopes.